Question

The standard electrode potential of Zinc is $0.76V$. What would be the potential of $0.1M$ zinc electrode?
A) $0.8196\;V$
B) $0.7895\;V$
C) $0.9484\;V$
D) $0.7508\;V$

Answer 1

As we know that standard electrode potential is basically that value of electrode potential when the temperature is fixed at ${25^\circ }C$, pressure is at $1\;atm$ and concentration of solution is considered as $1M$ and the difference of electrode potential generates electricity in an electrochemical cell.

Complete answer:
As we know that electrode potential is defined when a metallic rod is dipped into its own solution where a charge is developed after some time over the metallic rod with respect to the solution and the potential difference created is known as the electrode potential. It is denoted by ${E_{cell}}$. At standard conditions of temperature, pressure and concentration of solution, these parameters are fixed and then the electrode potential is called the standard electrode potential which is denoted as $E_{cell}^\circ$.
We also know that the formula for calculating the electrode potential is given as below:
${E_{cell}} = E_{cell}^\circ - \dfrac{{0.0591}}{n}\log \dfrac{{[anode]}}{{[cathode]}}$, Where $n$ is the charge on the ions.
Now, we are given that $E_{cell}^\circ = 0.76$ and the concentration of zinc electrode is given as $0.1M$. We also know that zinc will have a $+ 2$ charge. So, by putting all the values in the above formula we will get:
${E_{cell}} = 0.76 - \dfrac{{0.0591}}{2}\log (0.1)$
$\Rightarrow {E_{cell}} = 0.76 - \dfrac{{0.0591}}{2}( - 1) \\\ \Rightarrow {E_{cell}} = 0.76 + 0.0295 \\\ \Rightarrow {E_{cell}} = 0.7895\;V \\\$
Therefore, from the above calculation we can say that the potential of zinc electrode is found to be $0.7895V$.

And hence, the correct answer is Option B.

Note: Always remember that all the metallic electrodes are reversible with respect to their ions present in the solution. By convention, standard hydrogen electrons (SHE) are taken as the reference electrode and considered to have a potential of zero voltage. Also it is impossible to measure the accurate value of single electrode potential directly.